Log into your Gmail account with your username and password.
Open the mail.
To display the email headers,
Click on the inverted triangle beside Reply. Select Show Orginal.
You may copy the headers and use my IP address detection script to ease the process. Or if you want to manually find the IP address, proceed to 5.
Look for Received: from followed by the IP address between square brackets [ ].
Received: from [xx.xxx.xx.x] by web31804.mail.mud.yahoo.comIf you find more than one Received: from patterns, select the last one.
Track the IP address of the sender